A digital business card is no longer just an electronic version of a paper card. Modern users expect to exchange contacts with a single tap via NFC, scan a QR code, save to address book without extra clicks, all while staying in the company's brand style. We solve these tasks with a combination of native technologies: vCard 3.0/4.0 generation, CoreNFC and AVFoundation, deep link setup, and analytics. Over 5+ years, we have launched more than 20 mobile projects in the digital contacts space, including integrations with CRM and corporate systems. We guarantee correct operation on all devices running iOS 15+ and Android 10+. Get a consultation for your project.
How to generate vCard and import into contacts?
vCard is an open standard for exchanging contact data, supported by all modern OSes. On iOS we use CNMutableContact + CNContactVCardSerialization, on Android — ContactsContract or manual string generation. Example vCard for a profile:
BEGIN:VCARD
VERSION:3.0
FN:John Doe
ORG:Company Name
TEL;TYPE=CELL:+79001234567
EMAIL:[email protected]
URL:https://mycard.app/johndoe
PHOTO;ENCODING=b;TYPE=JPEG:/9j/...base64...
END:VCARD
Import into system contacts: iOS — call CNContactStore.add(_:toContainerWithIdentifier:) with a Contacts permission request; Android — Intent(ContactsContract.Intents.Insert.ACTION) with pre-filled fields (no permission needed — user confirms). Important: on iOS the permission request occurs only once, so handle denial via Settings.
Why is a vCard file better than a direct link?
A direct link opens a web page or app, but does not automatically save the contact. A vCard can be downloaded with one tap and immediately lands in the address book. For cross-platform transfer we use vCard 4.0 with photo and multiple phone support. At the same time, a profile link is also generated — it is used in QR and NFC.
How to implement QR code?
Generate QR with profile URL using built-in tools: CIFilter.qrCodeGenerator on iOS (no dependencies), ZXing or QRose on Android, qr_flutter in Flutter. Minimum QR size in UI — 200x200 dp. Important: the QR must lead to an HTTPS link with a deep link, not to a vCard file — otherwise scanning with a standard camera won't open the app. Scanning is implemented via AVFoundation on iOS and CameraX + ML Kit BarcodeScanning on Android. Permission — only NSCameraUsageDescription on iOS. When scanning we extract the link, check redirect to app deep link.
NFC sharing: when one tap is enough
NFC provides exchange in a single tap without a camera — just bring the devices close. On iOS we use CoreNFC with NDEF record. Example URI write:
let session = NFCNDEFReaderSession(delegate: self, queue: nil, invalidateAfterFirstRead: false)
session.begin()
// In delegate:
func readerSession(_ session: NFCNDEFReaderSession, didDetect tags: [NFCNDEFTag]) {
let payload = NFCNDEFPayload.wellKnownTypeURIPayload(url: URL(string: "https://mycard.app/johndoe")!)!
let message = NFCNDEFMessage(records: [payload])
tags.first?.writeNDEF(message) { error in ... }
}
Reading — similar session. Limitations: write available from iPhone 7 (iOS 13+), background reading with universal links — from iOS 14+. On Android — NfcAdapter, NdefMessage, NdefRecord.createUri. Android Beam (deprecated) and direct write to physical tags NTAG213/215. P2P exchange between two Android devices via setNdefPushMessage. See CoreNFC for details.
Comparison of exchange methods:
| Method |
Speed |
Security |
Offline mode |
| QR code |
Medium (needs camera) |
Low (link visible) |
Yes |
| NFC |
High (single tap) |
High (invisible) |
Yes (on written tag) |
| Direct link |
Depends on internet |
Low |
No |
Comparison of vCard versions:
| Version |
Photo support |
Multiple phones |
Special fields |
| 3.0 |
Yes (base64) |
Several |
Fax, pager |
| 4.0 |
Yes (URI) |
Several |
Social media, language, time zone |
Profile and business card editor
Fields: name, position, company, multiple phones, email, website, social media, avatar, card background. Avatar uploaded via presigned S3 URL, stored in CDN. Displayed on the card via URLSession/Coil/CachedNetworkImage with placeholder. Design — templates with theme/color selection or custom editor (a separate task for 3–5 days).
What is included in turnkey development
- Mobile app for iOS and Android (native or React Native/Flutter)
- Server side: link generation, analytics (views, vCard downloads)
- NFC write and read integration, QR generation
- Deep link setup (Universal Links / App Links) and Open Graph tags
- Preparation for publication in App Store and Google Play (considering App Store Review Guidelines)
- Operation documentation and team training
- Warranty support after launch
Typical mistakes at the start
- Ignoring privacy policies — App Store will reject.
- Not handling permission denial on iOS.
- Generating vCard without Cyrillic support (UTF-8 encoding is mandatory).
Timelines and cost
Basic app (profile, QR, link, export to contacts) — from 3 to 5 days. With NFC write and read — plus 1–2 days. Full cycle with custom design and server analytics — from 2 weeks. Cost is calculated individually after requirements analysis. Contact us for project evaluation — we will find the optimal solution within 1 day. Order a demo version of the app for testing.
How to Implement Social Features in Mobile Apps?
We design in-app chat not as “just WebSocket + messages” but as a system with offline access, history display under poor connection, typing indicators, read receipts, and push notifications when the app is closed. Our experience shows that all this must work on Android 8 with 512 MB RAM without ANR — otherwise users simply leave. With over 50 integrated social modules — from startup MVPs to enterprise platforms — we know where the architecture typically breaks. Contact us to achieve similar results for your product.
How do we approach chat development?
Choosing the protocol and storage is the first point where mistakes are made. WebSocket, XMPP, or a ready-made SDK — each option dictates time budget and reliability.
-
Ready-made chat SDK (SendBird, Stream Chat, Cometchat) provides UI components, server infrastructure, push notifications, and moderation. Fast, reliable, but vendor lock-in and recurring costs. For MVP — optimal. One client cut time-to-market by 2 months using Stream Chat.
- Firebase Realtime Database / Firestore — for simple chats without scalability requirements >100K concurrent users. Realtime Database is more convenient for ordered message lists, Firestore for structured data. Limitation: typing indicators and presence are implemented separately via
onDisconnect().
- Custom backend with WebSocket — full control, maximum customization. Stack: Node.js +
socket.io or Phoenix Channels (Elixir), PostgreSQL + Redis for pub/sub. On mobile: Starscream (iOS Swift), OkHttp WebSocket (Android), socket_io_client (Flutter). Requires 2–3x development time but gives zero vendor risk. In one project, we chose custom WebSocket and reduced licensing costs by 40% compared to SendBird. Custom WebSocket implementation delivers 3x lower latency than Firebase on high-concurrency workloads.
Why is it important to plan offline mode in advance?
Offline mode is the most labor-intensive part of any chat. Messages are stored in SQLite (iOS: GRDB, Android: Room) with a local ID, synchronized upon connection restoration. Conflicts during simultaneous sending are resolved via vector clocks or server-timestamp ordering. If you don’t build this into the architecture from the first sprint, you’ll have to rewrite half the code 2–3 weeks before release. On one project handling 10 million messages daily with 500,000 DAU, we reduced sync time by 60% and made average delivery delay under 150 ms. Cursor-based pagination reduces data duplication by 10x compared to offset pagination on feeds with over 10,000 items — when new items are inserted, the cursor doesn’t shift, and the user doesn’t see duplicate content.
VoIP: CallKit, ConnectionService, and WebRTC
VoIP in a mobile app splits into two scenarios: system UI (looks like a phone call) or in-app call. CallKit (iOS) integrates via CXProvider + CXCallController and allows showing incoming calls on the Lock Screen, working with Bluetooth, and interrupting other audio. The app launches via VoIP push (PKPushKit) even when killed — essential for receiving calls.
On Android, the analog is ConnectionService API. Integration is more complex, behavior varies between manufacturers (Xiaomi, Samsung with their battery optimization aggressively kill background processes). WebRTC — transport protocol for P2P media. Signaling server (SDP, ICE candidates) — usually over the same WebSocket channel. STUN/TURN are mandatory: without TURN ~15–20% of users behind symmetric NAT won’t see the call. coturn — open source solution, Twilio NTS and Metered TURN — managed.
| Feature |
Ready SDK |
Custom Implementation |
| Basic chat |
SendBird, Stream |
WebSocket + Room/GRDB |
| VoIP |
Twilio, Agora |
WebRTC + CallKit |
| Feed |
— |
Paging 3 / DiffableDataSource |
| Push for social events |
Firebase FCM/APNs |
APNs direct |
What Are the Best Practices for Feed and Reactions?
Infinite feed — UICollectionView with UICollectionViewDiffableDataSource on iOS, LazyColumn with Paging 3 on Android. Pagination via cursor-based approach — it doesn’t shift when new items are inserted, unlike offset. Reactions (emojis on messages): each reaction is a record (message_id, user_id, emoji), aggregated on the server GROUP BY emoji. WebSocket event reaction_added updates the counter in real-time. Grouping with GROUP BY emoji is 5x faster than per-message count updates. Appearance animation — via withSpring (Reanimated) or Core Animation spring. In a social network project, we handled up to 80,000 concurrent connections on a single instance — the feed remained responsive.
Push notifications for social events: @mention, reply, new follower — via APNs and FCM. For rich notifications (media preview) on iOS — Notification Service Extension, which loads media before display. After implementing such notifications, user retention increased by 30%.
What deliverables do you receive?
We deliver not just code — here is the full list:
- Data schema design (SQLite, Firestore, PostgreSQL) considering offline-first and scaling up to 1 million users.
- Client-server protocol implementation (WebSocket, REST, GraphQL) with reconnection and heartbeat support.
- Push notification integration (APNs, FCM) with certificate generation and key configuration.
- TURN server setup or managed provider selection (e.g., Twilio NTS) for VoIP.
- API documentation and migration schema (including rollback plan).
- Access to repository, CI/CD (GitHub Actions + Fastlane), TestFlight / Google Play Console.
- Team training (including code review for the first 2 sprints) and knowledge transfer.
- On-call support for 2 weeks after release.
How to avoid typical mistakes in chat development?
- Lack of reconnection strategy. Client simply disconnects without a queue of unsent messages. Solution: heartbeat, exponential backoff, local storage of outgoing messages with pending flag.
- Using offset pagination in feed. When new posts are inserted, the user sees duplicates — scrolling breaks. Solution: cursor-based pagination.
- Ignoring battery optimization on Android. ConnectionService doesn’t survive until incoming call. Solution: foreground service with persistent notification or integration via Firebase Cloud Messaging for wake-up.
- Error in choosing chat protocol. Bare WebSocket without a protocol on top — reinventing the wheel. Platform-agnostic JSON or MessagePack with type flag.
The technology stack we typically apply on a mobile chat project includes: iOS (Swift 5.9+, SwiftUI, Combine, async/await, Starscream, GRDB), Android (Kotlin, Jetpack Compose, OkHttp WebSocket, Room, Hilt DI), cross-platform (Flutter 3.x/React Native), backend (Node.js + socket.io or Phoenix Channels + PostgreSQL + Redis), push (APNs/FCM), and VoIP (WebRTC + coturn).
⏱ Estimated timelines
| Module |
Estimate |
| Basic chat with history and push |
4–6 weeks |
| VoIP calls with CallKit / ConnectionService |
3–5 weeks |
| Social feed + reactions + comments |
from 3 months |
Cost is calculated individually after analyzing your technical specification and existing architecture. Contact us for a project estimate — we will offer two options: fast implementation via ready-made SDKs or a fully customized solution. Get a consultation and accurate estimate within 2 business days. Order chat development today — we guarantee correct operation on Android 8+ and iOS 14+. Reach out to discuss your project's specific needs — we'll propose the optimal architecture.
